moodle/backup/db/backup_mysql.php

<?PHP  //$Id$
//
// This file keeps track of upgrades to Moodle's
// backup/restore utility.
// 
// Sometimes, changes between versions involve 
// alterations to database structures and other 
// major things that may break installations.  
//
// The upgrade function in this file will attempt
// to perform all the necessary actions to upgrade
// your older installtion to the current version.
//
// If there's something it cannot do itself, it 
// will tell you what you need to do.
//
// Versions are defined by backup_version.php
//
// This file is tailored to MySQL

function backup_upgrade($oldversion=0) {

    global $CFG;

    $result = true;

    if ($oldversion < 2003050300 and $result) {
        $result = execute_sql("CREATE TABLE `{$CFG->prefix}backup_ids` (
                        `backup_code` INT(12) UNSIGNED NOT NULL, 
                        `table_name` VARCHAR(30) NOT NULL, 
                        `old_id` INT(10) UNSIGNED NOT NULL, 
                        `new_id` INT(10) UNSIGNED,
                         PRIMARY KEY (`backup_code`, `table_name`, `old_id`)
                     )
                     COMMENT = 'To store and convert ids in backup/restore'");
    }

    if ($oldversion < 2003050301 and $result) {
        $result = execute_sql("ALTER TABLE `{$CFG->prefix}backup_ids`
                         ADD `info` VARCHAR(30)");
    }

    if ($oldversion < 2003050400 and $result) {
        $result = execute_sql("ALTER TABLE `{$CFG->prefix}backup_ids`
                         MODIFY `info` VARCHAR(255)");
    } 

    if ($oldversion < 2003050401 and $result) {
        $result = execute_sql("CREATE  TABLE  `{$CFG->prefix}backup_files` (
                                  `backup_code` INT( 10  ) UNSIGNED NOT  NULL ,
                                  `file_type` VARCHAR( 10  )  NOT  NULL ,
                                  `path` VARCHAR( 255  )  NOT  NULL ,
                                  `old_id` INT( 10  ) UNSIGNED,
                                  `new_id` INT( 10  ) UNSIGNED,
                               PRIMARY  KEY (  `backup_code` ,  `file_type` ,  `path`  ) 
                               ) COMMENT  =  'To store and recode ids to user & course files.'");
    }

    //Finally, return result
    return $result;

}

?>